The present invention is related to a Venetian blind slat control mechanism, comprising a set of first string ladders suspended between a head rail and a bottom rail of a Venetian blind for holding a plurality of equally spaced slats thereon, and a set of second string ladders whose upper ends are attached to a pair of guide sliding members connected to a linkage actuating plate and controlled by an operational cord attached to the linkage actuating plate thereof; whereby the operational cord is simply drawn to trigger the linkage mechanism thereof and synchronically lift the second string ladders so as to alternatively collect the slats in pairs in an easy and speedy manner without tilting the slats due to uneven pulling force applied thereto. Besides, the operational cord is mounted to one end of the head rail opposite to a lift cord so as to avoid confusing both cords in operation and achieve the best using status thereof.
Please refer to FIG. 1. A conventional Venetian blind slat control mechanism is made up of a Venetian blind 10 having a first string ladder 11 and a second string ladder 12 sequentially mounted to a plurality of slats 13 and respectively crossing the length of a lower rail 14 into U-shaped forms. Positioning slide posts 151 and a first and second pulley seats 152, 153 are respectively disposed at both ends of a head rail 15 for both ends of the first and second string ladders to respectively wind there-through and extend downwards there-from. When the first string ladder 11 is pulled downwards, the slats 13 of odd or even numbers will be actuated to raise upwards, each overlapping with the slat 13 above in pairs to augment the light-passable space as shown in FIG. 2. When the second string ladder 12 is pulled downwards, the slats 13 will keep gathering up from bottom to top in a sequence. A mounting seat with an adjustment member is adapted inside the head rail 15 for retaining a ladder tape (without shown in the diagram) to tilt the slats 13 into different angles thereby.
There are some drawbacks to such conventional Venetian blind slat control mechanism. First, the first and the second string ladders 11, 12 are suspended downwards from the same side of the head rail 15. In practical use, it's easy to confuse the two string ladders 11, 12 and require a repetition of the operation thereof. Besides, in case pulling force is unevenly applied onto both ends of the first or the second string ladders 11, 12, the slats 13 can easily get tilted and result in an inconvenient operation thereof. Second, the first string ladder 11 is wound across the length of the bottom rail 14 thereof. In case of a great pulling force applied thereto, the first string ladder 11 tends to raise upwards the bottom rail 14 and sequentially gather up each slat 13 from bottom to top, losing the function to pile up the slats 13 in pairs. Thus, the conventional Venetian blind slats mechanism is more difficult to manipulate in operation thereof. Third, the first string ladder 11, winding across the length at the inner side of the bottom rail 14, must first actuate the bottom rail 14 before extending through the first pulley seat 152 to suspend downwards there-from, which can waste quite a lot of efforts and pains in the operation thereof.